Process for making articles of quartz glass



J. SCHARL.

PROCESS FOR MAKING ARTICLES 0F QUARTZ GLASS.

APPLICATION FILED FEB. 8. 1919.

1,375,657. A Patented Apr. 19; 1921.

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PROCESS FOR MAKING ARTICLES 0F QUARTZ GLASS.

APPLICATION FILED FEB.8,1919.

1,375,657, Patented Apr. 19, 1921.

2 SHEETS-SHEET 2.

M072 ard UNITED STATES JOHN SCHARL, 0F NEW YORK, N. Y., ASSIGNOR T0GENERAL CERAMICS PATENT OFFICE.

COMPANY,

0F JERSEY CITY, NEW JERSEY, A CORPORATION 0F NEW JERSEY.

Specification of Letters Patent.

Patented Apr: 19, 1921.

Application led February 8, 1919. Serial No. 275,688.

To' all whom z't may concern.'

Be it known that I, -JOHN SOHA'RL, subject of Hungary, citizen of theUnited States, and resident of the cit of'New York, in

the county of New Yor and State of New York, have invented certain newand useful Improvements in Processes for Making Articles of QuartzGlass, of which the following is a specication.

This invention relates to processes of producing articles of quartzglass and .is directed particularly to improvements 1n the well-knownprocess of reducing the quartz to plasticity in an electric resistancefurnace with a resistance core and then blowin the plastic mass intomolds.

his process requires very ra 1d handling of the plastic material and1iicult has been experienced in that the plastic cy inder of quartz'formed in the furnace cools in being removed from the furnace to themold and in the process of blowing the same out to the desired shape.

In one method of operation referred to in m copendlin ap lication forpatent Ser. o. 254,560, led eptember 18th, 1918, the resistance core isfirst withdrawn and the fused mass with the tubular openingformedtherein by the core,rthen removed to the mold. Y The cold air thusgets in through this Opening and chills the mass froml the inside whileit is bein chilled on the outside as well. In the mol the chilling ofthe mass continues and especially in those processes where coldcompressed air is used for blowing the plastic mass out into a desiredshape.

In my present process, I keep the entire fused mass plastic much lon erthan has been possible with processes o like character heretofore usedso that more time is afforded for operation in blowing the fused massout into desired shapes, and greater accuracy of shape and higher gradesof guartz glass articles may be produced. This accomplish by removingthe fused mass from the furnace together with the core into the mold, sothat the core, still hot, may continue to heat the mass; b making use ofthe hot gases given Od' om the core to heat the mass without permittingthem to diduse therethrough; and by employing in the molding operation ahot gas under pressure, all as will hereinafter more fully ap ear.

y improved f process will now be described with the aid of theaccompanying drawing illustrating a preferred form of apparatus for thecarrying out thereof, and in whichv Figure 1 is a plan view of anelectric furnace adapted to carry out my improved process; y

Fig. 2 is a sectional elevation of the electric furnace showing thequartz disposed around and the inclosed resistance core;

Fig. 3 is a section taken along line 3 3 of Fig. 2;

Fig. 4 is a sectional elevation of a mold showing the plastic masspositioned there- 1n ready to be blown into the desired shape; F Figi 5is a section taken along line 5'5 of ig. 6 is a view showing the mass ofquartz fused after passage of the electric current and read to beremoved to the mold, the parts of7 the shell of the `furnace having beenmade to fall apart, and the bottom of the fused mass having been pressedtight by a pair of tongs,'and

Fig. 7 is a section cut on line 7-7' of Fig; 6. y he quartz is fused inan electric' resistance furnace consisting of a shell 10 and aresistance core 11 held between the electrodes l2 and 13.v Current issupplied to the electrodes as by the leads 14 and 15. A two-part jacket16 of heat resistant material, such as carbon or graphite is positionedin the shell and within this. jacket is placed a fine grade of silica 17from which the quartz articles are to be formed. Outside of this jacket,the shell is filled with heat insulating means, as for example coarsesilica 18. Surrounding the resistance core 11 is the tube 19 of heatresistant material such as carbon or graphite forming a spacetherebetween and the core wherethrough vthe as formed at the core mayescape, the tu e preventing said gas from dili'using into the .fusedmass of quartz.

In a preferred form of construction shown in Figs. 1 and 2, theresistance core is pressed down in position against the bottomelectrodeby the weight of the top electrode secured to the metal bar 21which is pivoted as at 22 so that the top electrode may be swung upwardout of the Way whenl removing t e fused mass.

Inasmuch as when the silica is yfused it becomes somewhat conductive thecurrent may pass through it and through the jacket and Vthus fuse someof the coarse silica on the outside of the jacket. This may causedifficulty in preventing the halves of the jacket from falling apart. ltherefore provide vertical members 23 of refractory material such ascarbon or graphite spaced a little fromthe jacket to prevent the 4coarsesilica therebetween and the latter from frisingagainst it.

he carrying out of my process will now be readily understood. Thejacket, 16 is positioned in the furnace and the core inserted in thetube 19 and the silica filled in around the tube. rlhe current is thenpassed until the silica is fused into a plastic cylinder7 the gas formedat the resistance core during the fusing operation escaping through thetubular space 20. The two parts of the shell 10 are then pulled apartand allowed to fall into the position shown in Fig. 6, the two halves ofthe jacket 16 falling apart at the same time, as shown. The mass is thenclosedA at the bottom in any suitable manner, as by pressing it tightwith the tongs 24. The top electrode is then swung upward and the fusedmass withdrawn from the furnace together with the core into the mold 25where it is blown out into articles of desired shape such as shown at26. The hot core keeps the mass plastic while it is being removed andwhile in the mold, while the hot gases escaping upward through thetubular space 20 also help keep the mass hot, no cold air getting intothe space 20 as the fused mass has already been closed at the bottom. Inblowing the plastic quartz into molds, employ a hot gas under pressurepreferably steam. The handling of .the plastic quartz in the mold mustbe very rapid and by the use of a preheated gas such as steam, I obtainthe desired pressure and at the same time do not permit the lastic massto harden too quickly. The lowing out process may be carried out asfollows: The plastic mass closed at the hottom havin been placed in themold, an airtight joint may be procured at the top by pressing the topof the plastic mass against the nozzle 29 by means of the plates 30 andthe bolts 31. Thisnozzle 29 is made preferably of highly heat resistantmaterial, such as carbon or graphite and the steam injecting tube orblow-pipe 32 may be threaded or in any other suitable way connectedthereto.

It will of course be understood that what makes it possible to blow thefused'mass out in the mold with the core in position, is

thus, allowing the compressed thin becomes fravile under the influenceof the heat and as the blowing operation proceeds, it is blown into themass and totally geraete disappears, leaving no trace in the finishedproduct. j

I have described my newly improved process with reference to the makingof smali `articles of glass such as shown at 26. It

will be noted that as these are blown the dishes when finished have theclosed bottom due to their being blown in the walls of the mold. lnblowing 'the larger articles, as for example large rucibles, a verticalmold is used and in order to provide the bottom for the crucible, thefused mass, instead of being pressed tight at the bottom against thecore may be forced beneath the core. ln this way the fused mass isclosed at the bottom and at the same time there s material completelycovering the hot core so that in blowing a complete Crucible may be hadhaving no hole in the bottom.

Having thus described my invention, I claim as new and desire to secureby Letters Patent:

1. rThe process of making articles of quartz glass consisting in heatingthe quartz into a plastic mass in an electric resistance furnace about aresistance corefclosing the bottom of the fused mass, then removing thesame from the furnace together with the hot core and blowing the massout into desired shape. a, n

2. "lhe process of making articles of quartz glass consisting in heatingthe quartz into a plastic mass in an electric resistance furnace aboutan inclosed resistance core, closing the bottom of the fused mass, thenremoving the saine from the furnace together with the hot core andblowingthe mass out into desiredshape.

3. The process of making articles ofY quartz glass consisting in heatingthe quartz into a plastic mass in an electric resistance furnace about aresistance core, closing the bottom of the fused mass, removing thefused mass from the furnace together with the hot core, placing the samein a mold and pressing the open end thereof around a nozzle, thenblowing a preheated gas under pressure therethrough substantially asdescribed.

4. The process of making articles of quartz glass consisting in heatingthe quartz into a plastic mass in anielectric resistance furnace aboutan inclosed resistance core, closing the bottom of the fused mass,removing the fused mass from the furnace toether with the hot core,placing the same in a mold and ressing the open end thereof around anozz e, then blowing a preheated gas under pressure therethrough substantially as described.

Signed at New .York city in the county of New York and State of New Yorkthis 3rd day of February A. D. 1919.

- Joint senaat;

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